1. Field of the Invention
The present invention concerns an apparatus for handling layers of palletized goods.
2. Description of the Prior Art
In order to make effective and inexpensive, and to simplify distribution of goods, most goods are sold on pallets, preferably the so-called EU pallets (800xc3x971200 mm). A widespread need has developed to also dispatch orders comprising lesser amounts of goods in a correspondingly effective way. Statistically it appears that many orders for small shops actually consist of consignments of goods most often consisting of very few layers or maybe just a single layer of palletized goods.
Until now several attempts have been made to mechanize such a layer-wise subpartitioning of palletized goods of every kind without success, including goods packed in cardboard packings, goods in single bags or sacks, goods in bundled bag packings or even foil encased bottled goods on a carrying bottom of cardboard. It has been attempted to develop a mechanical system for destacking in layers of palletized goods and subsequent restacking the individually destacked layers using a new, composite pallet which may be handled in a correspondingly effective way in final distribution as the usual whole pallets.
U.S. Pat. Nos. 3,406,938 and 3,229,953 describe a lifting device and an item holder using relatively complicated lifting or holding faces which consist of a large number of lesser chambers that are open toward the lifting face and the holding face, respectively. For lifting or holding of for example plate shaped items with different outer shapes or sizes in the printing industry it is known to use lifting or holding faces with a differentiated vacuum chamber system that is with a number of uniform, but individually connected chambers, which by means of a valve system may be connected with one or more vacuum sources in such a way that sheets or plates with individual shapes or sizes may be lifted or held fast with one and the same lifting or holding face.
EP-A-550114 describes a lifting device for lifting odd size items. The lifting means comprise suction means connected to a large number of suction cups. Each suction cup has means arranged inside the cup for blocking the connection to the suction means, when the cup is not in contact with an item to be lifted.
The invention is a new and improved apparatus for handling layers of palletized goods and comprising a vertically displaceable lift head with a mainly horizontal suction face which is substantially adjusted in size for a pallet, for example an EU-pallet, and which consists of a large number of downwardly openly suction chambers arranged for being moved downward against the upper side of an upper layer of individually or groupwise packed goods on a pallet, and which via individual valves is connected with a vacuum source preferably integrated in the lift head. The apparatus is arranged for co-operating with a depalletizing system. The individual valves between the suction chambers and the vacuum source comprise ball valves with very light thin walled spherical valve bodies being confined in the suction chamber by means of side projections or by a suitable lower holding net interacting with upper round valve openings with downward preferably spherical valve seats and arranged for being shut off if the relevant suction chamber is not blocked downwards by contacting the upper side of the goods at the uppermost pallet layer. This apparatus makes possible by means of simple measures mechanizing destacking in layers of individual goods from a pallet and subsequent reformation of new pallets with layers of individual goods.
In accordance with the invention the lift head along the outer sides of the suction face comprises means for exerting an inwardly directed pressure on at least the lower part of the outer sides of the goods of the upper pallet layer. By means of simple measures there is hereby achieved a new and improved apparatus which makes possible to handle multiple different types of palletized goods in layers with great certainty.
Notably, by means of the apparatus according to the inventionxe2x80x94where suction lift is combined with a squeezing (inwardly directed pressure) actionxe2x80x94lifting of pallet layers of foil packed bottles is achieved with great certainty where otherwise a great possibility exists of false air gaps at lateral directions because bottle packings usually have upwardly decreasing cross-sections. It has even proved possible to lift a pallet layer where apertures appear in the layer, either because some packings have been removed from the layer, or because the cross-sectional shape or the size of the packing simply is not a multiple of the cross-dimensions of the pallet layer.
The apparatus according to the invention is suitably thus designed that the means for exerting an inward pressure constitute inflatable bags arranged at respective outer sides of the lift head within a pressure absorbing outer casing thereof.
With the purpose of ensuring a very simple and suitable construction, the apparatus according to the invention may advantageously be thus designed that between the vacuum source and the suction chambers there is an air distribution chamber which at a lower, preferably horizontal, wall plate is designed with a common shut-off valve of a circle of mutually separated valve openings arranged in the wall plate and of a valve plate rotatably suspended therein and designed with a corresponding circle of valve openings. The valve plate is arranged for activation by means of a pneumatic cylinder inserted between the wall plate and a radial arm of the valve plate.
The apparatus according to the invention may furthermore be suitably designed so that the means for exerting an inward pressure furthermore are arranged in a vertically adjustable way relative to the lift head, so that the active area which is squeezed with inward pressure may be adjusted according to the height of the actual goods in respective pallet layers.
The means for exerting inward pressure may be used in lifting pallet layers of relatively light, fragile goods, for example groupwise foil packed non-slanting plastic cups by means of an evenly distributed, less powerful suction. The apparatus according to the invention may advantageously be designed so that each of the suction chambers comprises arresting means arranged to prevent the valve balls abutting on the valve seats for shutting off the ball valves. In a simple way, the arresting means may be constituted by a common wire net extending through the respective suction chambers above the valve balls, and which may be moved downward for preventing abutment of the valve balls against the valve seats.
As mentioned, the vertically displaceable lift head preferably comprises the vacuum source which preferably is a powerful centrifugal fan with an axial inlet port being connected with the air distribution chamber. The apparatus according to the invention is arranged for being connected to a pressurized air source which, among other things is used for activating the rotatable valve plate and for inflating the bags which are emptied of air again by coupling to the suction side of the vacuum source. With the intention of also mechanizing the subsequent subpartitioning of a pallet layer, the apparatus according to the invention may thus advantageously be so designed that the depalletizing system comprises a support plate arranged for carrying a layer of palletized goods and for being displaced between a receiving position under the lift head and a delivery position beside the lift head, and a pushing device arranged for pushing a layer palletized goods from the support plate and further onto a conveyor for dividing the palletized goods.
Suitably, the apparatus according to the invention may be further designed so that the surface of the support plate is wholly or partially provided with a friction facing designed to retain possible intermediate cardboard when the pallet layer is pushed from the support plate to the conveyor for dividing the goods, and that the conveyor comprises means arranged for retaining possible intermediate cardboard for removal by retracting the support plate to the receiving position.